The present invention relates generally to devices for respiratory protection in contaminated environments, and more particularly to a protective mask having a transparent hood with filter 10 and one-way valving structure which provides a positive pressure inside the mask and prevents the ingestion of contaminants.
Prior art protective masks generally require external air sources for delivering air under pressure into the masks. In the valving structure of the invention, the user ingests air through a filter and first one-way valve and exhales through a second one-way valve which maintains positive pressure inside the mask. Excess pressure escapes around the peripheral seal or through a low resistance one-way valve. The valving arrangement of the invention minimizes the dead space volume of air which may be rebreathed with negative physiological impact.
It is therefore a principal object of the invention to provide a chemical and toxic fume mask for personal respiratory protection against noxious and contaminated environments.
It is another object of the invention to provide a protective respiratory mask effective against substantially all known nerve and blister agents.
It is a further object of the invention to provide an inexpensive, disposable respiratory protection mask.
It is another object of the invention to provide a respiratory protective mask sized for substantially universal personnel fit.
It is another object of the invention to provide a respiratory Protective mask having substantial (high) protection factor.
It is yet another object of the invention to provide a respiratory protective mask which is easily and quickly donned.
It is another object of the invention to provide a respiratory protective mask having a long shelf storage life and which is sufficiently compact and portable to be carried on the person.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.